1. Field of the Invention
The present invention is related to the field of retransmitting data through networks, and more specifically to devices, softwares and methods for dynamic bandwidth allocation for an asynchronous transfer mode connection of a network.
2. Description of the Related Art
Networks, such as the Internet, generally transmit data in an asynchronous fashion, which is also called asynchronous transfer mode (ATM). A network device, such as a router, receives data and then retransmits it to another router.
A problem with ATM is that data arrives at each router at varying rates. The router, however, reserves a fixed amount of bandwidth for retransmitting the arriving data. The reserved amount of bandwidth is sometimes not enough, while other times it is more than required.
Referring now to FIG. 1A, FIG. 1B, and FIG. 1C, the problem of the fixed amount of bandwidth is illustrated in more detail. A Router-X 12 receives through a connection 14 a group 22 of data packets. Router-X 12 is connected with a Router-Y 32 via a connection 34, and with a Router-Z 42 via a connection 44.
Referring now to FIG. 1B, at a subsequent phase, Router-X 12 stores group 22 of the received packets. In addition, Router-X 12 analyzes the destination of group 22, and determines that group 22 should be retransmitted to Router-Z 42. Accordingly, Router-X 12 establishes an ATM switched virtual circuit (ATM SVC) 46 within connection 44.
Referring now to FIG. 1C, Router-X 12 transmits to router-Z 42 group 22 of data packets via ATM SVC 46. After that ATM SVC 46 remains active, until it is un-established. Additional data groups from the same source and with the same destination may also use ATM SVC 46, without having to establish it again.
This is where the problems start. On the one hand, if no additional data groups are received for a while, ATM SVC 46 remains open anyway, with its bandwidth being unavailable from associated network resources. On the other hand, if a second group 52 of data packets is received which is larger than group 12, more bandwidth would be required. When not accommodated, the data is delayed, which results in jitter at the receiving end.
The problem arises because, once established, ATM SVC 46 has a fixed bandwidth. This fixed bandwidth is determined from a size of the first received group 22 of data packets.